Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 42: Poster Session II (Nanostructures at surfaces: arrays; Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: Other; Nanostructures at surfaces: Wires, tubes; Metal substrates: Adsorption of O and/or H; Metal substrates: Clean surfaces; Metal substrates: Adsorption of organic/bio moledules; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsorption of inorganic molecules; Metal substrates: Epitaxy and growth; Heterogeneous catalysis; Surface chemical reactions; Ab-initio approaches to excitations in condensed matter; Organic, polymeric, biomolecular films– also with adsorbates; Particles and clusters)

O 42.67: Poster

Mittwoch, 25. März 2009, 17:45–20:30, P2

Water clusters and thin films on clean and oxygen-adsorbed Ni(111) surfaces — •Stefan Wippermann und Wolf Gero Schmidt — Lehrstuhl für theoretische Physik, Universität Paderborn, Warburger Str. 100, 33098 Paderborn

Despite the importance of water-surface interaction for many technological applications and surface science, it is only poorly understood in many instances. Inspired by recent experimental [1] and theoretical work [2], we explore the adsorption of water on clean and oxygen-adsorbed Ni(111) surfaces using density functional theory. Calculations on the water adsorption geometries and vibrational frequencies were performed for a wide range of monomer, dimer, trimer and hexamer structures adsorbed on the p(2x2)-Ni(111)-O and clean Ni(111) surfaces [3]. While our results agree well with the experimental findings of Nakamura and Ito [1], they suggest a different interpretation in terms of mainly two candidate structures: (i) Formation of an ice Ih-like bilayer structure with the free OH-bonds pointing upwards along the surface normal, and (ii) Formation of cyclic buckled hexamers similar to the ones discussed in Ref. [4]. In the latter case, each water molecule forms an OH--O_ad(2x2) hydrogen bond with two different hydrogen bond types depending on the water molecule's normal position in the buckled hexamer.

[1] M Nakamura and M Ito, Phys Rev Lett 94, 035501, 2005.

[2] D Sebastiani et al., J Chem Theory Comput 1, 78, 2005.

[3] S Wippermann and W G Schmidt, Phys Rev B (submitted)

[4] A Michaelides and K Morgenstern, Nature Materials 6, 597, 2007.